1. Field of the Invention
The present invention relates to an imaging device and an imaging method.
2. Description of the Related Art
Generally, imaging devices having an autofocus function are known. As one of methods for achieving autofocus, a method utilizing a change in contrast in accordance with a focusing condition is known. In such a method, for example, if a subject has low contrast, it may be difficult to focus the subject. There are a variety of known techniques that are devised to perform accurate focusing for a subject that is difficult to focus, for example, a subject with low contrast.
For example, Jpn. Pat. Appln. KOKAI Publication No. 2009-069696 discloses the following technique. In an image obtained by image capture, a main region that is to be focused and a plurality of sub-regions around the main region are set. If it is difficult to perform focusing in the main region, a focusing control is performed by using information on focusing conditions in the sub-regions in addition to information on focusing conditions in the main region.
Furthermore, for example, Jpn. Pat. Appln. KOKAI Publication No. 2008-165044 discloses the following technique. Focusing detection regions are arranged in a central portion and peripheral portions of a captured image. It is determined whether or not the subject is a flat object based on focusing evaluation values in the central and peripheral portions. When the subject is a flat object, a focusing operation is performed based on the focusing evaluation values in the central and peripheral portions. When the subject is not a flat object, a focusing operation is performed based on the focusing evaluation value in the central portion.
In particular, in an imaging device to capture moving images, if a focus position changes, the state of changing will be recorded as a moving image. Therefore, in an autofocus operation when a moving image is captured, it is desirable that a rapid movement or unnecessary movement of a focus lens should not occur.